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Ministry of Agriculture, Food and Rural Affairs

Field Horsetail

Scientific Name: Equisetum arvense L.

Other Names: Horse-pipes, Joint-grass, Mare's-tail, prèle des champs, queue-de-renard, prèle commune

Family: Horsetail Family (Equisetacae) 

General Description: Perennial. Never has flowers or seeds but reproduces by spores and by horizontal underground stems (rhizomes). Leafless branches and complete absence of flowers.

Habitat: Field horsetail occurs in all parts of Ontario in depressional areas with poorly drained soils, as well as in sandy or gravely soils with good drainage such as railroad embankments and roadsides. An intense competitor, it can severely suppress crops and other plants.

Seedlings

  • Plant development starts with the appearance of stems that shrivel up and disappear
  • Soon afterwards shoots appear

Stems

  • Rhizomes are dark brown or blackish, spread out for long distances and are often 1 m (3 1/3 ft) below the ground surface
  • They send up numerous aboveground shoots but of 2 different types at different times of the year
    • Early spring-
      • Shoots are ashy-gray to light brown, unbranched, hollow, jointed stems
      • Each node (joint) surrounded by a toothed sheath
      • Tip of stem ending in a brownish, spore-producing cone
    • After the cones have shed their spores (early May) these whitish to light brown stems wither and die down
    • At the same time, the second type of shoot emerges from the ground-
      • Green, slender, erect, hollow stems
      • Leafless but with whorls of 6 to 8 branches at nearly every node
      • Each branch may branch again with whorls of smaller branches
      • Stems and branches surrounded by a small, toothed sheath at each node but never end in a spore-producing cone
  • Both kinds of stems are easily pulled apart at the nodes and can be fitted back together like sections of a stove pipe

Often Confused With
Corn Spurry

Caution:
It contains a substance which destroys vitamin B in animals. It is especially poisonous to young horses. Hay containing this weed may be more poisonous than fresh plants in the field.

Field horsetail, fruiting stage  Field horsetail (vegetative) Field horsetail emerging from wet soil  Field Horsetail. A. Vegetative shoot (Green). B. Spore-producing reproductive shoot (whitish to light brown) Horsetail in strawberries Field horsetail
Click to enlarge.